Astronomy Reports 

About: Astronomy Reports is an academic journal published by Springer Science+Business Media. The journal publishes majorly in the area(s): Galaxy & Stars. It has an ISSN identifier of 1063-7729. Over the lifetime, 2585 publications have been published receiving 18902 citations. The journal is also known as: Astronomy.

General catalogue of variable stars: Version GCVS 5.1

Abstract: Work aimed at compiling detailed catalogs of variable stars in the Galaxy, which has been carried out continuously by Moscow variable-star researchers since 1946 on behalf of the International Astronomical Union, has entered the stage of the publication of the 5th, completely electronic edition of the General Catalogue of Variable Stars (GCVS). This paper describes the requirements for the contents of the 5th edition and the current state of the catalog in its new version, GCVS 5.1. The complete revision of information for variable stars in the constellation Carina and the compilation of the 81st Name-list of Variable Stars are considered as examples of work on the 5th edition. The GCVS 5.1 is freely accessible on the Internet. We recommend the present paper as a unified reference to the 5th edition of the GCVS.

"RadioAstron"-A telescope with a size of 300 000 km: Main parameters and first observational results

Abstract: The Russian Academy of Sciences and Federal Space Agency, together with the participation of many international organizations, worked toward the launch of the RadioAstron orbiting space observatory with its onboard 10-m reflector radio telescope from the Baikonur cosmodrome on July 18, 2011. Together with some of the largest ground-based radio telescopes and a set of stations for tracking, collecting, and reducing the data obtained, this space radio telescope forms a multi-antenna ground-space radio interferometer with extremely long baselines, making it possible for the first time to study various objects in the Universe with angular resolutions a million times better than is possible with the human eye. The project is targeted at systematic studies of compact radio-emitting sources and their dynamics. Objects to be studied include supermassive black holes, accretion disks, and relativistic jets in active galactic nuclei, stellar-mass black holes, neutron stars and hypothetical quark stars, regions of formation of stars and planetary systems in our and other galaxies, interplanetary and interstellar plasma, and the gravitational field of the Earth. The results of ground-based and inflight tests of the space radio telescope carried out in both autonomous and ground-space interferometric regimes are reported. The derived characteristics are in agreement with the main requirements of the project. The astrophysical science program has begun.

Dark matter, density perturbations, and structure formation

Abstract: This paper provides a review of the types of dark matter that are thought to be fundamental components of the Universe, and their role in the origin and evolution of structures, together with some new original results concerning improvements to the spherical collapse model. In particular, we show how the spherical collapse model is modified when dynamical friction and tidal torques are taken into account.

Non-LTE effects in Na I spectral lines in stellar atmospheres

Abstract: The paper examines the statistical equilibrium of Na I in stellar atmospheres with a wide range of parameters: T eff=4000−12500 K, logg=0.0−4.5, and heavy element content [A] from 0.5 to −4.0. The effect of the “overrecombination” of Na I (i.e., excess relative to the equilibrium number density of Na I) is present over the entire range of parameters considered, and increases with T eff and luminosity. Na I lines are stronger than in the LTE case, so that non-LTE corrections to the sodium abundance, ΔNLTE, are negative. Eight Na I lines commonly employed in abundance analyses are used to construct the dependences of the non-LTE corrections on T eff, logg, and metallicity. The non-LTE corrections are small only for the Na I λλ615.4, 616.0 nm lines in main-sequence stars: |ΔNLTE| ≤0.08 dex. In all other cases, ΔNLTE depends strongly on T eff and logg, and a non-LTE treatment must be applied if the sodium abundance is to be determined with an accuracy no worse than 0.1 dex. The profiles of solar Na I lines are analyzed in order to empirically refine two types of atomic parameters required for the subsequent analysis of the stellar spectra. In the solar atmosphere, inelastic collisions with hydrogen atoms influence the statistical equilibrium of Na I only weakly, and the classical Unsold formula underestimates the van der Waals constant C 6. The empirical correction ΔlogC 6 is from 0.6 to 2 for various Na I lines. The sodium abundance in the solar atmosphere is determined based on line-profile analyses, yielding different results depending on whether the model atmospheres of Kurucz (logɛNa=6.20±0.02) or Holweger and Muller (logɛNa=6.28±0.03) are applied.

The mass of the compact object in the X-ray binary her X-1/HZ her

Abstract: We have obtained the first estimates of the masses of the components of the Her X-1/HZ Her X-ray binary system taking into account non-LTE effects in the formation of the H γ absorption line: m x = 1.8 M ⊙ and m v = 2.5 M ⊙. These mass estimates were made in a Roche model based on the observed radial-velocity curve of the optical star, HZ Her. The masses for the X-ray pulsar and optical star obtained for an LTE model lie are m x = 0.85 ± 0.15 M ⊙ and m v = 1.87 ± 0.13 M ⊙. These mass estimates for the components of Her X-1/HZ Her derived from the radial-velocity curve should be considered tentative. Further mass estimates from high-precision observations of the orbital variability of the absorption profiles in a non-LTE model for the atmosphere of the optical component should be made.